I'm probably throwing off the average, I'm running bare bottom in my 20g long. Personally I like the look of sand better than BB, and when I get my 40b up and running, I might use sand. But there are definite advantages of bare bottom. First, no worrying about flow blowing sand around when trying to tweak flow. Second, there's no nutrient or detritus trap that you constantly have to clean and maintain. Third, although this is a more rare event, if you ever swap tanks, you don't have to worry about disturbing the sand and moving the sand bed.
If you've never tried it before, I say go for it. You can always add sand a little at a time later if you don't like it. If the tank is bare bottom from the start, it will look less weird; you'll get used to the tank with no sand bed and it will look normal after a while.